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HOMESERVICE MANUALSCHEVROLET2006COBALT SS, 4D SEDAN, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 9 (COMPUTER/INTEGRATING SYSTEMS)DIAGNOSTIC INFORMATION AND PROCEDURESDTC U2100CONDITIONS FOR CLEARING THE MIL/DTC
2006 Chevrolet Cobalt SS, 4D Sedan, Standard

Conditions for Clearing the MIL/DTC

2006 Chevrolet Cobalt SS, 4D Sedan, StandardSECTION Conditions for Clearing the MIL/DTC
WARNING: This page is about a different car, the 2005 Saturn L300. However, it is still accessible from the selected car via links, so may be relevant.
  • A current DTC Last Test Failed clears when the diagnostic runs and passes after 3 consecutive drive cycles.
  • A current DTC clears and the MIL is turned OFF when the fault is no longer present.
  • A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the fault, or after 40 consecutive drive cycles.
DTC U2100

Step Action Yes No
Schematic Reference: Data Link Connector (DLC) Schematics 
Connector End View Reference: Master Electrical Component List in Wiring Systems
1 Did you perform the Diagnostic System Check - Vehicle? Go to Step 2  Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2
  1. Turn the ignition OFF.
  2. Disconnect the body control module (BCM), engine control module (ECM), and transmission control module (TCM) connectors.
  3. Test both the controller area network (CAN) high and low circuits for the following conditions:
    • A short to ground
    • A short to voltage
    • A short to each other
Turn the ignition ON, with the engine OFF when you test for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 Go to Step 5  Go to Step 3 
3
  1. Using the scan tool, clear the DTCs.
  2. Turn the ignition OFF.
  3. Reconnect each module one at a time, starting with the TCM, then the BCM, and finally the ECM.
  4. After each module is connected, check for U2100 in the ECM.
Does DTC U2100 reset after reconnecting each module one at a time?		 Go to Step 5  Go to Step 4 
4 Replace the module that resets U2100. Refer to Control Module References  for replacement, setup, and programming.
Did you complete the replacement?		 Go to Step 5  -
5
  1. Reconnect all modules not already connected.
  2. Use the scan tool in order to clear the DTCs.
  3. Turn the ignition switch OFF.
  4. Wait at least 10 seconds.
  5. Turn ON the ignition, with the engine OFF.
  6. Retrieve DTCs from the ECM.
Does the DTC reset?		 Go to Step 2  System OK
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.